Riffle



Aug. 10, 1937. I I w BELL 2,089,780

RIFFLE Filed July 9, 1955 Elma/whom Harry W. Bell Patented Aug. 10, 1937STATES PATENT FFICE RIFFLE Washington Application July 9, 1935, SerialNo. 30,460

2 Claims.

My invention relates to rifiles such as are employed for catching andsegregating gold values, particularly fine dust.

Placer mining or dredging operations always take place in relativelyremote spots, generally requiring packing in for considerable distancesover rough country. Weight is therefore an item of considerable moment.Replacement or repair of equipment is seldom easy to accomplish, andsuspension of operations because of break-down of equipment becomes aserious matter, especially where, as in certain parts of Alaska, theworking season is a comparatively short portion of the year.

Aside from the first object of all rifiles, namely, to catch the gold,and all of it, it is a primary object of this invention to provide ariille unit which is light in weight, durable, and readily repairable onthe spot, and which is therefore admirably suited for use under theconditions outlined above.

It is a further object to make a rifile of material which is largelywaste and available in large quantities, and which can therefore be madeand sold cheaply, a material fulfilling these requirements being rubbertire casing material, particularly but not essentially the tread portionor" such casing.

It is especially an object to provide a rifile which is efficient andrapid in saving the gold, so that large quantities of gold-bearinggravel and sand may be worked through the riffle, thus making iteconomically possible to handle larger quantities of material in whichthe gold-bearing content may be relatively low, for example, eventailings of old workings.

Since fine gold particles worked in a riffle will find their way intoseemingly impenetrable crevices it is a further object to provide arifile which, though it may be made of individual strips with spacerelements between them, may yet be made tight at all joints to preventsecretion of gold in the joints between the rilile elements and thespacers.

It is a still further object to provide a riffle which can be readilyhandled as a unit, and can be readily lifted and removed from thedeposited sand, clay and gold at clean-up times.

It is a further object to provide a rifiie which may readily be formedin various patterns to suit the individual taste or desire of the user.

A further object is to provide a riflle unit so formed that through theaction of the water, gravel, sand and the like moving thereover it willautomatically iree itself from any gravel which may tend to lodgebetween the rifile elements, thereby automatically preventing cloggingof the riflle units.

My invention comprises the novel riifie unit and the novel riiileelement and their relative combination and arrangement, as shown in theaccompanying drawing by way of illustration, and as will be made clearin this specification and more particularly defined by the claimsterminating the same.

Figure l is a perspective View, with parts broken away, showing two suchrifile units in a sluice box.

Figure 2 is in part an elevation and in part a section through such arifiie unit.

Figure 3 is a section taken transversely across a riffie unit ofsomewhat modified form.

The sluice box in itself forms no part of my present invention, and thatshown is merely a typical sluice box by way of illustrating the mannerin which my rifile unit may be incorporated in such a sluice box. Itcomprises the bottom 4, sides 40 and 4|, supporting and bracing elements42, and hold-down elements 43 secured inside the sides 49 and 4| to holdthe rifile units in place resting upon the bottom l.

In a typical form, illustrated in the drawing, the rifile unit comprisesa plurality of strips I cut from rubber tire casing material. Old solidrubber truck tires may also be cut into strips and used for thispurpose. Rods 2 pass through a number of such strips, spacer elements 3holding the latter spaced apart, and nuts 20, threaded on the rods, holdthe spacers and strips together so that the whole, in the formillustrated, comprises a grid in which the strips I are held on edge inparallel spaced-apart face-to-face relationship, and with the stripsextending transversely to the direction of water flow, indicated by thearrows F. Preferably the strips are so arranged that while generallyupright they are somewhat inclined to the direction of water flow, and Iconsider it preferable to leave the tread surface, when the strips aremade of tread material, as is preferable, on the upstream side of thewater flow, so that the natural transverse concavity of the materialtends to curve its upper edge downstream. This is shown in Figure 2.

An advantage of this is that there is presented first to rocks orgravel, as indicated at R, the comparatively thick, tough rubber of thetread, as the gravel rolls downstream, and in addition there is formed asharp edge on the downstream side, stifiened and reinforced by theembedded fabric Ill, over which the water riflies and eddies,

thus breaking up its direct flow and effecting rapid deposition of thegold, as indicated at G. It has been found that rifiies formed of metal,in addition to weighing excessively, wear away comparatively rapidlyunder the abrasive eifect of the sand and gravel, but the rubber, whilesufiiciently stiff to form the eddy currents, does not wear away, and byits inherent elasticity and flexibility yields somewhat to the poundingof the gravel, and is continually flexing, and it is a proven fact thatit does not wear away appre: ciably during a season.

To further the flexibility of the strips l, the rods 2 are spaced apartin the direction of the length of the strips I, so that there is left asub.- stantial portion of each strip which is unsupported, and thereforeflexible. This flexibility serves a further purpose in that a piece ofgravel tending to lodge or wedge itself between any two adjacent stripswill, by the flexing action of these strips, be squeezed and workedfree, so that the riiiie is selfcleaning and nonclogging.

Preferably the spacer elements 3 are formed of short lengths of rubbertubing, for example, comparatively stiif garden hose. Thus they arecompressible and their ends can be pressed tightly against the adjacentstrips i, which in themselves, of course, are somewhat compressible, bytightening up the nuts 21%, thereby completely closing any joint betweenthe spacers and the strips to prevent the entrance and secretion of goldin such crevices. Gold, when passed over rifiies, has the peculiarproperty of working into minute cracks and fissures, for example, intonail holes, and a considerable quantity of gold might otherwise workinto the holes through which the rods extend, or into the interior ofthe spacer elements 3, if the latter were not tightly pressed againstthe faces of the strips.

To make the unit easy to handle I prefer to employ frame elements suchas the angle irons 5 at each end of a unit. The unit thus formed may bemade of a size which is convenient for packing, and which is light inweight as compared to any riiile with which I am familiar, except onemade of wood, and wooden riiiles have the very serious disadvantage thatthey wear out rapidly. Such a unit as this, composed of strips whichhave paraliei smooth faces, provides no anchoring means which willresist pulling the unit from the sand, clay and the like, indicated at Sin Figure 2, which lodges between the riiile units. At cleanup time theriiile must be lifted from this mass of material to enable the collectedmaterial to be washed down the sluice box to affordaccess to the gold,and it has been found in practice that such riiile as this is notdifficult to lift out, even though the collected material may be of aclaylike nature, which in some instances becomes practically a cement,greatly resisting eflorts to remove the riiiie.

As mentioned above, it is preferable that the tread surface of thestrips be placed on the upstream side. These tread surfaces, though madeof worn tires, will ordinarily have left on them certain irregularitiesof the tread pattern (see Figure 3) and these irregularities servefurther to break up and riflie the water flowing over the unit.

While the strips have been shown extending transversely of the sluicebox, this is only one way in which my invention may be manufactured, andindeed the pattern may be any which suits the convenience of themanufacturer or the desire of the user. Furthermore, instead of straightupper edges, the upper edge of each strip may be scalloped, as shown atH in Figure 3, or otherwise edge, upstanding from the bottom 4 of thesluice box, since the fabric plies l6 effectively resist wear and serveto stiifen the riiiles, but the strips might be otherwise placed withoutdeparting from the spirit of my invention as defined in the claims.

the action of the water, sand, gravel and gold, and this. vibration willtend to segregate the material and to effect additional riiiiing of thewater in addition to the property previously mentioned of freeing rockswhich might tend to lodge between the strips, and this vibration,therefore, which cannot be present in a riiile made of any nonyieldingmaterial, presents a further advantage in this riflie.

What I claim as my invention is:

The strips i, being flexible, will vibrate under 1. A riflie unit fordisposition in a sluice box,

comprising a plurality of flexible strips of rubber material, eachhaving a scalloped edge, and supporting said strips disposed on edge inspacedapart, parallel, face to face relation, with their scalloped edgesuppermost, and with the scallops on adjacent strips arranged inrelatively staggered relationship.

2. A rifiie unit for disposition within a sluice box, comprising aplurality of readily flexible strips disposed on edge in face to facerelation,

rods extending through apertures in the strips from end to end of theunit, and spaced apart lengthwise of the strips, spacing tubes having abore considerably larger than the rods, surround ing the rods, and ofsuch an outside diameter and interposed between adjacent strips in suchrelationship thereto as to engage the strips from substantially theirlower edges to above their centers, to stiffen the major part of eachstrip,

while leaving the strips upper edges free to flex by the flow ofmaterial over the strips, and means to press the spacing elements intocontiguous gripping engagement with the strips.

1 HARRY W. BELL.

